1. Field of the Invention
The present invention is directed to support elements for short arc lamp electrode rods. More specifically, such support elements of the present invention include a collar, at least one coil spring and a placement piece for each coil spring and provide significant passage areas for circulation of gas within the arms of the lamp.
2. Information Disclosure Statement
Short arc lamps have been in use for many years and typically involve xenon or other gas within a quartz glass envelope with an anode and cathode separated by a gap across which an arc passes during use. Xenon is particularly useful because it emits a daylight-like light.
The electrodes are attached to electrode rods in opposite positions to each other and these rods extend into quartz arms for contact with electrical connectors. The electrode rods are supported so as to be centrally located axially within the quartz arms, and so as to align the electrodes with one another.
U.S. Pat. No. 5,369,329 by Austad et al. discloses a short arc discharge lamp having a quartz envelope with a bulb and a plurality of arms having a specified cross-section, and wherein one or more electrode rods are supported within the lamp arms for specific alignment. Support elements for the electrode rods are made of high temperature metal and have a flat central portion with a central orifice of sufficient dimension to permit one of the electrode rods to pass into the central orifice, and have at least two legs, and preferably four legs, radially extending from the flat central portion. The legs have outer portions terminating with pods formed at substantially right angles to the flat central portion of the support element, the legs being of sufficient length to fit the support element within a specified cross-section of the envelope arms so as to contact an inside surface of the envelope arms with the pods. There is also provided means for securing the support elements within the envelope arms.
U.S. Pat. No. 4,559,472 describes a discharge lamp or arc lamp with specified support element structures for the electrode rods (referred to as "elongated electrodes"). The high pressure arc lamp described has a quartz glass enclosure defining a discharge space and quartz arms extending away from the discharge space are provided with elongated electrodes (assemblies) extending respectively through the quartz arms. These electrode assemblies carry respective electrodes at their inner ends and the electrode assemblies are sealed hermetically to the respective envelope portion. In order to support the electrodes within the envelope, respective support elements are fitted around the electrodes in spaced relation to the envelope and quartz arms. Means including a respective resilient element engaging each support member, are provided to hold the support elements in their axial position around the respective electrode assemblies. The resilient elements are each held between the respective electrode and the inner surface of the respective support element to continuously urge the axially outer surface of the support element resiliently against the respective inner diameter of the quartz arms.
Unfortunately, the lamp described in U.S. Pat. No. 4,559,472 above retains the gases within the bulbous portions or bulb of the envelope and the sputtering and blackening which occurs limits the illumination and the life of the lamp.
U.S. Pat. No. 4,463,281 describes another arc lamp wherein the electrode rods are supported by spring biased quartz plugs. These plugs are of less mass than the previously described prior art electrode supports and are spring loaded toward the center, with notches or openings cut out for gas to flow through. However, these spaces do not permit or induce significant enough gas flow to substantially reduce the negative sputtering effects described above. In fact, larger cut outs cannot be made without causing or risking cracking or shattering of the glass supports.
U.S. Pat. No. 3,715,616 to Lavering describes and illustrates and an electrode support structure for use in a short arc lamp. The structure includes a ring having a plurality of flaps formed therein. Struts are attached to the electrode and to the flaps. These struts may be straight and may be abutted to the electrode. The flaps can bend to minimize the stresses created by the contraction and expansions of the struts relative to the ring during the temperature cycling of assembly and operation.
U.S. Pat. No. 3,497,752 to Peterson discloses a quartz halogen lamp having a connector coil at the end of a filament leg to physically support the filament and make electrical connection to lead-in wire. The coil encircles the lead-in wire and has two warms in an overlapping, compressive engagement which constricts the coil in its direction of winding and thereby clamps it on the wire. A similar coil, the arms of which press against the lamp envelope, supports the interior end of the filament mount.
U.S. Pat. No. 3,250,941 to Wilson et al. discloses a compact source lamp including a vitreous envelope having a tubular portion, pinch seals at opposite ends of the envelope through which extend inleads each including a foil portion hermetically sealed through the pinch seal and a rod-like portion projecting into the envelope. The electrodes have their outer ends attached to the inner ends of the rod-like portions and define a short interelectrode gap. The foil portion is associated with at least one of the electrodes and is insufficiently rigid to support the electrode vertically. At least one support member comprises a wire coiled around the one electrode at its outer end and has an expanded turn bearing against the wall of the vitreous envelop at the tubular portion.
U.S. Pat. No. 3,211,941 to Sanden et al. describes and illustrates a filament support for tubular incandescent lamps having a support member formed from a single length of wire bent to form a retroverted mid-section which engages the envelop wall and two clamping legs which cross over at least one point adjacent the filament coil and which have clamping portions engaging the filament coil at least at three points around its periphery and which extend divergently therefrom into engagement with the wall of the tubular envelope.
U.S. Pat. No. 2,962,615 to Anton discloses a radiation detector tube including a gastight envelope with a hollow axially symmetrical conducive cathode, a radiation-permeable window sealed across one end of the cathode, an insulator sealed at the other end of the cathode and an anode wire mounted in cantilever fashion and sealed to the insulator. The anode wire extends coaxially within the cathode and terminates adjacent the radiation permeable window. There is also an anode support structure including an insulating sleeve positioned along said anode wire and adjacent the unsupported end of the anode and extending beyond the free tip of the anode, and a support member which engages the insulating sleeve and the cathode to hold the insulating sleeve in fixed positions to prevent the anode from vibrating.
U.S. Pat. No. 2,749,461 to Hierholzer, Jr. et al. relates to electric discharge devices in which a high pressure mercury vapor lamp is resiliently supported inside of an outer envelope of the reflector type wherein the radiations emitted thereby may be directed to a predetermined direction through a dome portion of the outer envelope.
U.S. Pat. No. 2,562,887 to Beese discloses a vapor lamp having an glass envelope resistant to caesium at a range of temperatures with electrodes therein and having a discharge between the electrodes and the envelope upon the application of electrical energy thereto. The envelope is generally cylindrical and includes an ionizable medium.
Great Britain Patent Application No. 2,106,312 A discloses a high pressure discharge lamp with electrodes in relatively long leg parts and having a reinforcement abutment. The reinforcement abutment is a quartz annulus fused to the inside of the leg parts and resilient clips which fit around shanks of the electrodes and bear against the abutments to centrally locate and support the shanks.
Thus, while various supports have been developed for short arc lamp electrode rods, none suggest or teach the present invention collar with coil springs with their configurations and advantages described herein.